This invention relates to a jack for positioning and supporting an object, such as heavy mechanical equipment or a large stationary machine.
Large stationary machines, such as air compressors, components of a rolling mill, or other industrial equipment, must be rigidly secured to their foundations and in many instances must be accurately positioned relative to other equipment. Typically, these large machines are mounted on reinforced concrete foundations and are accurately positioned thereon by means of jack screws or the like. With the machine supported in its desired position, precision-machined shims or chocks are installed between the support points or pads of the machine and the foundation so that the machine is accurately positioned and supported in its selected position. These precision-machined shims are costly and time consuming to manufacture and install. With the machine supported on the shims, a grouting mix, such as an aggregate-containing epoxy resin or the like, is poured around the shims. After the grouting mix has hardened, anchor bolts are tightened to secure the machine to the foundation and prevent any upward or lateral movement.
Typically, machinery which is mounted in the above-described manner operates continuously and is subject to vibrational and other cyclic loading. Over a period of time, this loading may cause the grouting to degrade and deteriorate so that the machine must be periodically reset on its foundation. With conventional machine mounting system, the machine must be removed from its foundation and the grouting mix chipped away. The machine is then repositioned, reshimmed, regrouted and rebolted to the foundation. This resetting procedure is costly and frequently entails several weeks' time during which the machine is out of operation or "down". This may require shutdown of an entire plant or a product line with consequent great loss of revenue.
Adjustable machine supports, such as shown in U.S. Pat. No. 3,695,352, are known which use steel balls within a piston and cylinder arrangement to support a machine. However, these adjustable machine supports, particularly where access to the support is limited, may be difficult to adjust for accurate positioning of the machine. Also, systems, such as shown in U.S. Pat. No. 3,194,853, are known in which an epoxy resin is injected into voids in the grouting beneath a machine base to fill the voids.
As shown in my U.S. Pat. Nos. 3,978,574 and 4,046,354, a method of and apparatus for positioning and supporting a machine are disclosed in which the machine is raised to a selected level by a series of hydraulic jacking units pressurized with a hardenable hydraulic working fluid (e.g., epoxy resin) and then sealed once the machine is moved to its selected position. The hardenable fluid within the jacking units is permitted to harden thereby to internally fix the jacking units in their adjusted positions. After the jacking units have been fixed, grout is poured around them. However, since the epoxy resin inside the jacking units hardens substantially without expansion or contraction, the grout surrounding the jacking units merely holds the jacking units in position and does not bear any substantial portion of the weight of the machine or the cyclical or vibrational loading of the machine. In the event these jacking units must be reset, the grout surrounding the units must be removed and the machine reset on new jacking units.